The present invention relates to a vacuum evaporation device, which is more particularly used in molecular jet epitaxy installations.
A vacuum evaporation installation, which is e.g. used in the production of semiconductors by molecular jet epitaxy, generally comprises a main enclosure connected to pumping means (primary and secondary pumps) and containing the substrates to be treated, as well as one or more evaporation cells containing the material or materials to be evaporated.
In order to permit the recharging of these cells with various materials and without breaking the vacuum of the main enclosure, installations have been developed in which the evaporation cell to be recharged is detachable and is connected to the main enclosure by a metal bellows. When the bellows is compressed, the cell is in the normal evaporation position in the enclosure, whilst when the bellows is stretched, the cell is retracted out of the main enclosure into a small auxiliary chamber. This chamber can be separated from the main enclosure by the action of a tight ultra-high vacuum valve. Such an installation makes it possible to recharge the cell while only placing the auxiliary chamber under atmosphere again.
Although satisfactory from certain respects, such installations suffer from disadvantages due to the very significant travel which has to be given to the bellows (more than 500 mm), which leads to:
high costs, due both to the cost of the bellows and that of the guidance and translation system, which must be very accurate to ensure a correct alignment over a considerable distance, PA1 a risk of pollution of the enclosure by the effect of degassing operations of the long bellows, PA1 high weight, PA1 large overall dimensions, which is prejudicial to access to the other cells.